Medical device coating configuration and method for improved lubricity and durability

ABSTRACT

Medical devices and methods for making and using the same. An example medical device includes a slotted tubular member and a coating disposed over the tubular member. The coating may define one or more coating gaps therein.

FIELD OF THE INVENTION

The present invention pertains to intracorporeal medical devices, forexample, intravascular guidewires, catheters, stents, and the like aswell as improved methods for manufacturing medical devices. Moreparticularly, the invention relates to medical devices with coatings.

BACKGROUND

A wide variety of intracorporeal medical devices have been developed formedical use, for example, intravascular use. Some of these devicesinclude guidewires, catheters, stents, and the like. Of the knownmedical devices, each has certain advantages and disadvantages. There isan ongoing need to provide alternative medical devices as well asalternative methods for manufacturing medical devices.

BRIEF SUMMARY

The invention provides design, material, and manufacturing methodalternatives for medical devices. An example medical device includes aslotted tubular member and a coating disposed over the tubular member.The coating may define one or more coating gaps therein.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present invention.The Figures and Detailed Description which follow more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a plan view of an example medical device disposed in a bloodvessel;

FIG. 2 is a perspective view of a portion of an example medical device;

FIG. 3 is a perspective view of the portion of the example medicaldevice shown in FIG. 2 with a coating disposed thereon;

FIG. 4 is a side view of an example coating gap;

FIG. 5 is a perspective view of a tubular member with an example maskingmember disposed therein; and

FIG. 6 is a cross-sectional view taken through line 6-6 in FIG. 3.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about,” whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

FIG. 1 is a plan view of an example guidewire 10 disposed in a bloodvessel 12. Guidewire 10 may include a distal section 14 that may be, asis well known in the art, generally configured for probing deep withinthe anatomy of a patient. Guidewire 10 may be used for intravascularprocedures according to common practice and procedure. For example,guidewire 10 may be used in conjunction with another medical device suchas a catheter 16. Of course, numerous other uses are known amongstclinicians for guidewires and other similarly configured medicaldevices.

Turning now to FIG. 2, here it can be seen that guidewire 10 may includea tubular member 18 having a plurality of slots 20 formed therein.Tubular member 18 may be made of a metal, metal alloy, polymer,metal-polymer composite, or any other suitable material. Some examplesof suitable metals include stainless steel, such as 304V, 304L, and316LV stainless steel; mild steel; nickel-titanium alloy such aslinear-elastic or super-elastic nitinol, nickel-chromium alloy,nickel-chromium-iron alloy, cobalt alloy, tungsten or tungsten alloys,MP35-N (having a composition of about 35% Ni, 35% Co, 20% Cr, 9.75% Mo,a maximum 1% Fe, a maximum 1% Ti, a maximum 0.25% C, a maximum 0.15% Mn,and a maximum 0.15% Si), hastelloy, monel 400, inconel 825, or the like;other Co—Cr alloys; platinum enriched stainless steel; or other suitablematerial. In general, the materials chosen for tubular member 18 providetubular member 18 (and/or guidewire 10) with a number of desirablecharacteristics. For example, materials such as nickel-titanium alloysmay provide a desirable level of flexibility and torque-transmittingcharacteristics that may help guidewire 10 be suitable for a number ofdifferent interventions.

Slots 20 may be micromachined or otherwise created in tubular member 18,and may be configured to make tubular member 18 more flexible inbending. It is worth noting that, to the extent applicable, the methodsfor forming slots 20 can include, for example, any of the appropriatemicromachining methods disclosed herein or any of micromachining andother cutting methods disclosed in U.S. Pat. Publication No.2003/0069522A1 and/or U.S. Pat. No. 6,766,720, the entire disclosures ofwhich are herein incorporated by reference. These and other cuttingmethods may also include saw cutting (e.g., diamond grit embeddedsemiconductor dicing blade), etching (for example using the etchingprocess described in U.S. Pat. No. 5,106,455, the entire disclosure ofwhich is herein incorporated by reference), laser cutting, electrondischarge machining, or the like. It should be noted that the method formanufacturing guidewire 10 may include forming slots 20 in tubularmember 18 using any of these or another manufacturing step.

Various embodiments of arrangements and configurations of slots 20 arecontemplated. Slots 20 are generally arranged to be perpendicular to thelongitudinal axis of tubular member 18. This arrangement can,alternatively, be described as having slots 20 lying within a plane thatis normal to the longitudinal axis of tubular member 18. In someembodiments, slots 20 may be formed part way through tubular member 18,while in other embodiments, slots 20 may extend all the way throughtubular member 18. Any one or more of the individual slots 20 may extendonly partially around the longitudinal axis of tubular member 18. Slots20 may be formed in groups of two, three, or more slots 20, which may belocated at substantially the same location along the axis of tubularmember 18, and may be substantially perpendicular to the longitudinalaxis.

A coating or coating material 22, such as a polymeric coating, may bedisposed on the outer surface of tubular member 18 as shown in FIG. 3.Coating 22 may be a lubricious, a hydrophilic, a hydrophobic, aprotective, a medicated, or other type of coating. Suitable materialsfor coating 22 may include silicone, polysulfones, polyfluorocarbons(such as TEFLON), polyolefins such as polyethylene, polypropylene,polyesters (including polyamides such as nylon), polyurethanes,polyarylene oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxylalkyl cellulosics, algins, saccharides, caprolactones, and the like, andmixtures and combinations thereof. Any other suitable polymer may alsobe utilized without departing from the spirit of the invention.

In some embodiments, coating 22 may be a single, homogeneous layer of asingle polymer. Alternatively, coating 22 may include a homogenous ornon-homogenous blend of polymers. For example, coating 22 may differ incomposition along the length of guidewire 10. In other embodiments,coating 22 may have multiple layers of the same, different, or blendedpolymers that are either homogeneously or non-homogeneously arranged.Other embodiments include materials that are blended among themselves orwith formulated amounts of water insoluble compounds (including somepolymers) to yield coatings with suitable lubricity, bonding, andsolubility. Some other examples of such coatings and materials used tocreate such coatings can be found in U.S. Pat. Nos. 6,139,510 and5,772,609, which are incorporated herein by reference.

Coating 22 may be made from, doped with, or otherwise include aradiopaque material. Radiopaque materials are understood to be materialscapable of producing a relatively bright image on a fluoroscopy screenor another imaging technique during a medical procedure. This relativelybright image aids the user of guidewire 10 in determining its location.Some examples of radiopaque materials can include, but are not limitedto, gold, platinum, molybdenum, palladium, tantalum, tungsten ortungsten alloy, plastic material loaded with a radiopaque filler, andthe like.

Because tubular member 18 is often designed with particular flexibilityand torque-transmitting characteristics in mind, for example, it may bedesirable to apply coating 22 to tubular member 18 in a manner thatcompliments, has the desired (and sometimes minimal) impact on, orfurther refines these characteristics. For example, tubular member 18may be designed to be highly flexible, for example for probing deepwithin the vasculature, and coating 22 may be disposed on tubular member18 in a manner that has a minimal or predictable impact on theflexibility of tubular member 18.

In at least some embodiments, coating 22 may be configured to have oneor more coating gaps 24 formed therein. Coating gaps 24 are generallyarranged in a manner that has the desired effect (or “non-effect”) onthe flexibility of tubular member 18. For example, coating gaps 24 maybe disposed over some or all of slots 20. These arrangements may, forexample, allow tubular member 18 to remain highly flexible by reducingthe amount of coating material 22 disposed at slots 20.

The manner in which coating gaps 24 are disposed over slots 20 mayfurther allow tubular member 18 to be flexible. For example, the coatinggaps 24 may have a length L_(cg) that may be shorter than a length L_(s)of the slots 20 as shown in FIG. 4. In addition, coating gaps 24 mayhave a width W_(cg) that may be the substantially the same as a widthW_(s) of slots 20 as seen in FIG. 4. This arrangement may desirablyimpact the flexibility of tubular member 18 as described in more detailbelow. In alternative embodiments, L_(cg) may be substantially the sameor longer than L_(s) and/or W_(cg) may be longer or shorter than W_(s).It should be noted that any of these configurations can be analogouslyapplied to embodiments where slots 20 have a major axis that extends inthe longitudinal direction.

As seen in FIG. 4, the W_(cg) is generally longer than L_(s). In someembodiments, W_(cg) can be about 1.5 to about 500 times longer thanL_(s). In other embodiments, W_(eg) can be about 1.5, 2, 2.5, 3, 3.5, 4,4.5, 5, or more times longer than L_(s). However, this need not be thecase as the relative lengths/widths can vary on a number of factorsincluding the shape of slots 20. For example, slots 20 as shown in FIG.2, generally have a long axis that lies in a plane that is normal to thelongitudinal axis of tubular member 18. Other embodiments arecontemplated, for example, where slots 20 have a long axis that lieslongitudinally aligned with the longitudinal axis of tubular member 18.In these embodiments, L_(s) may be longer than W_(cg) at proportionssimilar to what is described above or any other suitable arrangement.

In at least some embodiments, coating gaps 24 can be seen as beinglongitudinally shorter but yet laterally or circumferentially just aswide as slots 20. Because coating gaps 24 may be just as wide as slots20, coating 22 may be more durable and resilient while still being ableto provide a suitable “coating” (e.g., lubricious, hydrophobic, or othercoating) to tubular member 18. In addition, because coating gaps 24 maybe longitudinally shorter than slots 20, not only is coating 22 moredurable and resilient by virtue of this arrangement, coating gaps 24define a space extending in the circumferential direction about tubularmember 18 and over slots 20 that allows for lateral deflections intubular member 18 to occur without having to overcome significantresistance created by the presence of coating material 22 adjacent orwithin slots 20 (e.g., where tubular member 18 may be bending).

In addition, combinations of the aforementioned arrangement withalternative arrangements may allow for differing flexibilitycharacteristics. For example, some embodiments of tubular member 18include slots 20 arranged in longitudinal rows, for example, asindicated in FIG. 2 as a first slot row 20 a, a second slot row 20 b,and a third slot row 20 c. Coating gaps 24 may be similarly arranged inlongitudinal rows, for example, as indicated in FIG. 3 as a first gaprow 24 a, a second gap row 24 b, and a third gap row 24 c. Someembodiments of guidewire 10 are contemplated that utilize one or morerows of coating gaps 24 (e.g., row 24 a, row 24 b, row 24 c, orcombinations thereof) disposed over one or more rows of slots 20 (e.g.,row 20 a, row 20 b, row 20 c, or combinations thereof). For example,some embodiments include row 24 a of coating gaps 24 disposed over row20 a of slots 20. One or more of the remaining rows 20 b/c of slots 20may be free of coating gaps 24. For example, FIGS. 2/3 illustrates thatrow 20 b of slots 20 is free of coating gaps 24 in row 24 b. Thisparticular arrangement may decrease the flexibility (e.g., stiffen)along rows 20 b and define guidewire 10 as having a favored or moreflexible bending direction (e.g., laterally in a direction that isperpendicular to row 20 a and/or row 24 a). Similarly, some embodimentsincludes two rows 24 a/c of coating gaps 24 disposed over two rows 20a/c of slots 20. Analogously, this arrangement may result in a zone offlexibility or plurality of favored or more flexible bending directionsalong rows 20 a/c and/or rows 24 a/c and a stiffened region along row 20b and/or 24 b.

In addition to the aforementioned desirable characteristics associatedwith having coating gaps 24 in coating 22, a number of additionaladvantages are contemplated. For example, the inclusion of coating gaps24 may help to smooth out the exterior of guidewire 10, therebyimproving the lubricity and handling of guidewire 10. Additionally, thepresence of coating gaps 24 across slots 20 allows for guidewire 10 tobend freely over slots 20 when force is applied. Because coating 22 isdiscontinuous over slots 20, the amount of chipping of coating material22 at, for example, the edges of slots 20 is reduced. In addition, themethods for applying coating 22 and defining coating gaps 24 allow forcoating 22 to be applied to tubular member 18 without the need of abonding or tie layer. This may help to reduce the manufacturing cost ofguidewire 10.

The process for applying coating 22 to tubular member 18 may include anysuitable method such as dip coating, spraying, and the like. Definingcoating gaps 24 in coating 22 may include a wide variety of methods. Forexample, coating material 22 may be dissolved, suspended in, orotherwise mixed with a solvent that can be subsequently removed (e.g.,by evaporation or any other suitable manner) to leave coating gaps 24.Some examples of solvents include water (such as deionized water),alcohol (e.g., isopropyl alcohol (IPA) and ethyl alcohol), ethers (e.g.,methanol, propanol, isopropanol, and ethanol), toluene,N-methyl-2-pyrrolidone (NMP), tetrahydrofuran, methylene dichloride,methylethylketone, dimethylacetate, ethyl acetate, and their mixturesand combinations thereof. It should be noted that the word “solvent” isused herein for convenience and is not intended to limit the inventionto any particular class or kind of material.

In at least some embodiments, the solvent acts like a “mask” or maskingagent/solution that, in a sense, blocks a portion of coating 22 suchthat when the masking solution is removed, a newly defined coating gap24 is left behind. Removing the solvent or masking agent may includeremoving the solvent over a particular slot 20, a particular row or rowsof slots 20, all of slots 20, at a location away from slots 20, orcombinations thereof. The process of removing the solvent the mayinclude curing the coating 22. For example, an oven (or other chamberused for heating and/or drying) may be used to cure the coating 22and/or evaporate or dissipate the solvent. In some embodiments,ultraviolet (UV) light sources or other radiation sources may be used tocure the coating 22 and/or evaporate or dissipate the solvent.Alternatively, the solvent may be removed by dissipation throughevaporation (e.g., at room temperature) and/or expulsion such as with avacuum or other expulsion means. Some additional details regarding thismasking-solution dipping methodology can be found in U.S. applicationSer. No. 11/509,204, filed on even date herewith and entitled “ELONGATEMEDICAL DEVICE AND METHOD OF COATING THE SAME”, the disclosure of whichis herein incorporated by reference.

Alternatively, the “masking agent” may include a structural barrierdisposed adjacent tubular member 18 in order to physically definecoating gaps 24. Turning now to FIG. 5, here it can be seen that one ormore masking members 25 may disposed within tubular member 18 andproject through one or more slots 20. Because masking member 25 extendsoutward beyond the outer surface of tubular member 18, application ofcoating 22 to tubular member 18 can be performed in a manner such thatcoating 22 does not cover masking member 25 or is otherwise removablefrom masking member 25. Thus, once coating material 22 is suitably driedand/or cured, masking member 25 can be removed, leaving behind newlydefined coating gaps 24.

In still other embodiments, coating gaps 24 can be defined by a suitablecutting and/or heating method. For example, coating gaps 24 may bedefined by laser cutting portions of coating 22 at the desired location.

Turning now to FIG. 6, here it can be seen that, in addition to tubularmember 18, coating 22, and coating gaps 24, guidewire 10 include otherstructures such as those commonly associated with guidewires. Forexample, guidewire 10 may include a core wire 26. Core wire 26 may bedisposed within a portion of tubular member 18. In some embodiments,core wire 26 may include one or more tapers or tapered regions 28.Guidewire 10 may also include other structures common to guidewires suchas a polymeric tip, a spring tip, one or more radiopaque markers, andthe like. The materials utilized for these structures and otheranalogous structures may include those disclosed herein or any othersuitable material.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of theinvention. The invention's scope is, of course, defined in the languagein which the appended claims are expressed.

1. A medical device, comprising: an elongate core member having aproximal end region and a distal end region; a tubular member disposedover the distal end region, the tubular member having a plurality ofslots formed therein, the plurality of slots having a width and alength, wherein the width is longer than the length; and a coatingmaterial disposed over the tubular member, wherein one or more coatinggaps are defined in the coating material, the coating gaps having awidth and a length, wherein the width is longer than the length; whereinthe length of the coating gaps is less than the length of the slots. 2.The medical device of claim 1, wherein at least some of the coating gapsdefined in the coating material are disposed over the slots.
 3. Themedical device of claim 1, wherein all of the coating gaps defined inthe coating material are disposed over the slots.
 4. The medical deviceof claim 1, wherein all of the slots have coating gaps disposedthereover.
 5. The medical device of claim 4, wherein all of the coatinggaps defined in the coating material are disposed over the slots.
 6. Themedical device of claim 1, wherein the slots are arranged into two ormore longitudinally-aligned rows and wherein the coating gaps defined inthe coating material are disposed over a single longitudinally-alignedrow of slots.
 7. The medical device of claim 1, wherein the slots arearranged into three or more longitudinally-aligned rows and wherein thecoating gaps defined in the coating material are disposed over at leasttwo of the longitudinally-aligned rows of slots.
 8. The medical deviceof claim 1, wherein the coating material includes a polymer.
 9. Themedical device of claim 8, wherein the coating material includes ahydrophilic polymer.
 10. The medical device of claim 1, wherein thewidth is about 1.5 to about 500 times longer than the length.
 11. Themedical device of claim 1, wherein the coating gaps are disposed over atleast some of the slots and wherein the width of the coating gapssubstantially spans the width of the slots.
 12. A medical device,comprising: an elongate core member having a proximal end region and adistal end region; a tubular member disposed over the distal end region,the tubular member having a plurality of slots formed therein; whereinthe slots have a width; a coating material disposed over the tubularmember, wherein one or more coating gaps are defined in the coatingmaterial at one or more positions over the slots; wherein the coatinggaps have a width and a length and wherein the width is longer than thelength; wherein the width of the coating gaps substantially spans thewidth of the slots; and wherein the slots are arranged into two or morelongitudinal rows and wherein the coating gaps defined in the coatingmaterial are disposed over a single longitudinal row of slots.
 13. Themedical device of claim 12, wherein the medical device is stiffer alongthe one or more longitudinal rows of slots that do not include thecoating gaps.
 14. The medical device of claim 12, wherein the slots arearranged into three or more longitudinal rows and wherein the coatinggaps defined in the coating material are disposed over at least two ofthe longitudinal rows of slots.
 15. The medical device of claim 14,wherein the medical device is stiffer along the one or more longitudinalrows of slots that do not include the coating gaps.